Creating a mod_rewrite rule in an htaccess file - .htaccess

Question

I am trying to create a mod_rewrite rule to direct people to a sub-folder. Currently the code looks as follows:
RewriteEngine On
RewriteCond %{HTTP_HOST} abcsite.com$ [OR,NC]
RewriteCond %{HTTP_HOST} ^!www\.abcsite\.*$
RewriteCond %{REQUEST_URI} !^/abc/.*$
RewriteRule (.*)$ /abc/$1 [L]
The redirect works if the user types www.abcsite.com, but not if they type abc.com. Is there something that I am missing or should do differently to make sure the user goes to the correct folder (regardless of how they type the URL)?
Side note: The htaccess file that I am dealing with is a Joomla file, so all contents of it deal with another Joomla site. I appreciate the help.

Answer 1

Because you have conditions for that.
RewriteCond %{HTTP_HOST} abcsite.com$ [OR,NC]
RewriteCond %{HTTP_HOST} ^!www\.abcsite\.*$
RewriteCond %{REQUEST_URI} !^/abc/.*$
All above rules will pass only its abcsite.com
You add following rules also then it work for abc.com too.
RewriteCond %{HTTP_HOST} abc.com$ [OR,NC]
RewriteCond %{HTTP_HOST} ^!www\.abc\.*$
RewriteCond %{REQUEST_URI} !^/abc/.*$
RewriteRule (.*)$ /abc/$1 [L]

Answer 2

There's a stray ! in your second condition. A ! in front of the pattern means that the condition is true when the regex doesn't match (like in the third condition). A ! inside the pattern is just a literal symbol.
The host conditions should be something like:
RewriteCond %{HTTP_HOST} ^abcsite\.com$ [OR,NC]
RewriteCond %{HTTP_HOST} ^www\.abcsite\.com$ [NC]
And in fact, they can be joined into a single condition (note, no [OR] here):
RewriteCond %{HTTP_HOST} ^(www\.)?abcsite\.com$ [NC]
Your third condition is intended to prevent redirect loops (/foo → /abc/foo → /abc/abc/foo → …). What it says is that the rule isn't applied if the request URL starts with /abc/. However, your actual redirect is an internal redirect: if a user accesses abcsite.com/foo, the server internally rewrites this to /webroot/abc/foo, but REQUEST_URI stays the same, /foo.
The reason this doesn't cause a redirect loop as it is is likely rewrite rules in abc/.htaccess which override this one once the redirect is done.
What should be checked instead in the third condition is the path matched by the rewrite rule:
RewriteCond $1 !^abc/
RewriteRule (.*) /abc/$1 [L]